Impact-tool.



J. J. PADBURY.

IMPACT TOOL.

APPLICATION FILED AUG.16,1909.

957,798. Patented May 10, 1910.

lfial.

UNITED STATES PATENT OFFICE.

JOHN JAS. PADBURY, OF PHILADELPHIA, PENNSYLVANIA.

IMPACT-TOOL.

seams.

T all whom it may concern:

Be it known that I, JOHN J. PADBLRY,

a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented certain Improvements in Impact-Tools, of which the following is a specification.

My invention relates to pneumatic impact tools of the valveless type, in which the inlet and exhaust ports are so arranged or disposed within the shell or wall of the cylinder with respect to the piston or hammer and its movement within said cylinder. that the hammer acts as its own valve; having a surface of suitable contour to enable it to perform this duty.

The object of my invention is to provide an improved impact tool of the valveless type having means for reducing the amount of pressure necessary to retract the piston or hammer after it has made the forward or working stroke, and for this purpose I reduce the striking end of the hammer and provide the same with a shoulder adapted to receive the motive fluid to effect the initial part of the return movement of said hammer.

A further feature of my invention, resulting from this construction is the cushioning of the blow of the piston or hammer, should the latter operate for any length of time after the cutting tool has been removed, through accident or otherwise, from its socket in the cylinder.

A still further feature of my invention is the means for locking the head or cappiece to the cylinder of the tool.

My invention is fully illustrated in the accompanying drawings, in which:

Figure 1, is a sectional view of my improved impact tool showing the piston in one position, taken on the line a-a, Fig. 2; Fig. 2, is a similar sectional view taken on the line Z)b, Fig. 1, showing the piston in another position, and Figs. 3, 4c, 5 and 6, are cross sectional views taken on the lines c-c, cZcZ, e@ and f-f, respectively, Fig. 1.

In the accompanying drawings, 1 represents a shell or cylinder having a central bore 1 in which a hammer or piston 2 is free to move in both directions. The piston or hammer is arranged to act upon the stem or a suitable tool fitted in the end or socket 3, of the cylinder, and said hammer is constructed so as to be adapted to act as a valve controlling the motive fluid which effects its movements. Air or other motive fluid un- Specification of Letters Patent.

Application filed August 16, 1909.

Patented May 10, 1910.

Serial No. 512,034.

der pressure enters the cylinder through a passage +t in the head or cap-piece of the tool and passes to a. cross passage 6 and thence to passages T in the wall of the cylinder from which it emerges through ports 8 into the bore of the cylinder, thence around the centrally reduced portion 9 ot' the hammer to a port 10, passage 11, and port 12 to rear end of the hammer, whereby the lat ter may be moved in the direction of the arrow :0, Fig. 1. After the hammer has completed half its stroke, the reduced portion 9 of the same opens a small port 15, communicating with a passage 16, which opens through a port 17 into a recess 18, at the impact end of the cylinder. The end of the hammer is provided with a reduced portion 19 forming the striking member, and also has a shouldered portion 20 formed at the point of junction between said striking member and the main body of the tool or hammer, and this shoulder 20 is adapted to enter the recess 18. As the shoulder enters the recess 18, it meets the how of fluid under initial pressure, and will begin the return stroke of the hammer; the motive fluid behind the piston being meanwhile exhausted through a port to exhaust passages 26 communicating with the atmosphere. The length of time the hammer or piston is un der the influence of initial pressure is relatively short as the piston or hammer cuts 03 the port 15 leading to the passage 16 soon after the hammer or piston begins its rear ward movement. It is sutlicient to fully retract the piston or hammer. however, and. by the time the latter has fully opened the lower exhaust port 27, it has closed the upper exhaust port and the hammer is therefore ready to receive the full pressure of the motive fluid passing around the reduced portion 9 of the piston to the ports and passages 10, 11 and 12, to make the return or working stroke. In addition to this construction the shoulder 20 has another function. As this shoulder fits exactly in the recessed portion 18 at the end of the cylinder adjacent to the striking end of the piston or hammer, it serves the purpose of cushioning the blow of said hammer or piston should the tool be removed for any purpose, before the flow of motive fluid is cut off.

A further feature of my invention is the means for locking the head or cap-piece 5 of the tool to the cylinder 1 of the same. This locking means consists of a substantially circular member 31 having one side out ofi, as at 32 and having the balance of its rim or edge notched or serrated, as shown at 33. Arranged to engage this notched or serrated portion of the member 31 is a bolt 34: brought into engagement with the toothed portion of said member by means of a spring 35. During the operation of screwing the head or cap-piece 5 into position at the end of the cylinder, the member 31 will have its straight side flush with the under side of said head so as not to interfere with the movement of the same; but when said head has been turned the limit of its movement, which has been previously determined; a notch 36 being provided at the end of the cylinder to receive the locking member 31, the latter will be turned so as to fit said notch and the head or cap-piece will be thereby positively locked against disengagement. This slot has one face arranged at an angle so as to take up part of the wear of the locking member and insure the action of the same each time the parts are fitted in place. The locking member 31 may be readily turned on its axis, after pressing the bolt 35 away from the same by means of a suitable tool, so as to bring its flat side flush with the upper surface of the head or cap-piece, thereby enabling the latter to be removed.

I claim:

1. In a pneumatic impact tool, the combination of a cylinder, a piston therein having a reduced end forming a shoulder, said cylinder having an annular recess adjacent the striking end of the tool to receive said shoulder, and a live air passage communicating with said recess.

2. In a pneumatic impact tool, the combination of a cylinder having a series of ports and passages in the wall of the same and an annular recess of reduced area formed in one end thereof, a live air passage leading to said recess, and a piston or hammer mounted within said cylinder and having a shouldered portion to enter said annular recess whereby movement of the tool in one direction may be controlled by motive fluid entering the passage leading to said recessed portion.

3. In a pneumatic impact tool, the combination of a cylinder, a piston longitudinally movable in said cylinder, the wall of the latter being provided with ports and passages whereby movement of the piston can be controlled, means for supplying motive fluid to said cylinder, and a shoulder formed on the end of the piston or hammer adjacent to the striking portion of the same, the cylinder of said tool being recessed for the reception of the shouldered portion of the hammer and having a passage for motive fluid to act upon said shoulder of the hammer for the purpose of cushioning the blow and imparting to said hammer or piston the initial portion of the return stroke.

4. The combination in a pneumatic impact tool, of a cylinder, a cap-piece secured thereto and carrying inlet and exhaust ports for the motive fluid, means for securing said cap-piece in place comprising a toothed member carried by the cap-piece and arranged to fit a slot in the cylinder, and means for securing said toothed member in an adjusted position.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

JOHN JAS. PADBURY.

WVitnesses:

MURRAY C. BOYER, -WM. A. BARR. 

